Coronal heating and the importance of MHD waves

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AbstractThe Sun provides us with many interesting puzzles. One surprising result is that the solar photosphere is 100 times cooler than the overlying corona. The mechanism that heats the corona is related to the Sun's magnetic field but the exact physical process that transports energy from the solar interior up to the corona and deposits it there remains unknown. There are several possibilities but none have really been demonstrated theoretically.This project will examine a new self-consistent coronal heating model. It will investigate how a slow build-up of magnetic stresses can create the plasma inhomogeneities that can help short period waves damp efficiently. This project will solve the MHD equations, which govern plasma processes in the Sun, using numerical methods and an existing program, and will determine whether there is enough energy in the waves to maintain a coronal plasma at 1 million degrees. The advantage of the numerical modelling is that the correct coronal thermodynamics can be included so that the temperature and density of the plasma can be compared with current observations.Background and key issues to be addressedThere are various heating mechanisms that have been proposed and, traditionally, they have been split into two main categories, namely heating by waves and heating by magnetic reconnection. Heating by reconnection requires the slow storage of magnetic energy in the solar corona over a period of time as slow motions at the surface continually stress the magnetic field. This stored energy is then released rapidly through the triggering of magnetic reconnection. The triggering event can cause a subsequent avalanche of energy release events (Hood et al, Astrophys J, 817, 2016). Heating by waves assumes that the energy required to heat the corona is transported there by waves. These low amplitude waves have a short period that is much faster than the slow timescale for the storage method. This project will investigate wave heating mechanisms in combination with the slow stressing motions